make allocPixels throw on failure

src/gpu/SkGrPixelRef.cpp

 
 /*
  * Copyright 2010 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 
 
@@ skipping 152 matching lines @@
         left = subset->fLeft;
         width = subset->width();
         top = subset->fTop;
         height = subset->height();
     } else {
         left = 0;
         width = this->info().fWidth;
         top = 0;
         height = this->info().fHeight;
     }
-    if (!dst->allocPixels(SkImageInfo::MakeN32Premul(width, height))) {
+    if (!dst->tryAllocN32Pixels(width, height)) {
         SkDebugf("SkGrPixelRef::onReadPixels failed to alloc bitmap for result!\n");
         return false;
     }
     SkAutoLockPixels al(*dst);
     void* buffer = dst->getPixels();
     return fSurface->readPixels(left, top, width, height,
                                 kSkia8888_GrPixelConfig,
                                 buffer, dst->rowBytes());
 }